An airbag which has been quickly increasing in its installing rate in recent years as one of the safety parts for cars is used for such a purpose that, in car collisions, a sensor perceives the shock, gas of high temperature and high pressure is generated from an inflator and the airbag is quickly developed by the gas whereby the collision of the bodies or, particularly, the heads of a driver and a passenger to steering wheel, windshield, door glass, etc. is prevented and protected. In recent years, airbags for cars have been developed in their practical use not only for a driver seat and a passenger seat but also for knee airbags, side airbags, curtain airbags, etc. and installment of a plurality of airbags is now becoming common.
As regions and numbers of the installed airbags are increasing, there has been an increasing demand for making the weight and the size of an airbag system lighter and more compact and each of the parts of the system has been designed with a target of making the weight lighter and the size more compact. In view of such a background, airbags have been investigated for a plan of using a fabric where the yarn of small fineness is used or for a plan of reducing the type of elastomer of a coating textile and the coating amount.
For example, fineness of a filament used in a coating fabric for airbags is becoming finer from 940 dtex to 470 dtex and, in recent years, there has been a change to a fabric using the filaments where fineness is 350 dtex.
On the other hand, an elastomer resin which is coated to a coating fabric for airbags has been also changed from chloroprene to silicone resin. Further, its coating amount has been changed from 90-120 g/m2 to 40-60 g/m2 and, in recent years, it has been reduced to an extent of 25-40 g/m2.
Although considerable enhancement has been achieved by such a means in view of package ability, it is not still in a fully satisfactory level and there has been a demand for further reduction of the coating amount.
With regard to a coating fabric for airbags where the coating weight of silicone resin is reduced, there is a disclosure for an airbag where elastomer is unbalancedly present in terms of a coating thickness ratio of not less than 3.0 in the knotted area of the textile to 1.0 of textile yarn area which constitutes the textile (see Patent Document 1). Although this airbag is improved in terms of the package ability, it is difficult to satisfy the flammability in case the resin is unbalancedly present when the coating amount is adjusted to not more than 20 g/m2.
There is also a disclosure for a coating fabric for airbags where not less than 90% of the outer circumstances of the cross sections of warp and weft positioned at the resin-coated surface of the synthetic fiber textile are surrounded by said resin and the coating weight of the resin is not more than 20 g/m2 (see claim 2 of Patent Document 2). In this fabric, although the adhesion of the fabric to the resin is enhanced, the resin coating positioned on the textile surface is thin whereby breakage is apt to happen on the coating and the flammability is insufficient.